The crystal and the electronic structure of La2Li1/2Au1/2O4

The single crystal X-ray investigation of the compound (La2Li1/2Au1/2O4)-O- III yields a T'-type structure (Nd2CuO4) with an ordered distribution of Li and Au-III on the sites with square-planar coordination (space group Ammm; a = 5.768 Angstrom, b = 5.762 Angstrom, c = 12.166 Angstrom; c/a(b) = 2.16 5; a(Au-O) = 2.013(3) Angstrom). Though Cu-III possesses the same low-spin d(8)-configuration as Au-III, La2L1/2Cu1/2O4 adopts the ordered T-structure with strongly elongated CuO6 octahedra. The electronic and structural caus es of the different behaviour are discussed.